Power Vacuum Tubes Handbook

Abstract

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Pyrocarbon anti‐emission coatings for grid electrodes of powerful generator lamps

“…Powerful generator lamps [1,2] are now widely used in radio and television, radio communications, radar systems for both civil and military applications, in a number of modern technological installations, including those designed to accelerate charged particles and for the research in the field of nuclear physics and fusion. The output power level of such lamps ranges from units of kilowatts to 2.5 megawatts in continuous mode and up to 5 megawatts in the pulsed mode.…”

“…The main directions of improvement of powerful lamps are an increase in specific power per unit volume and an increase in durability with a high level of reliability [3]. The problem is solved by the search for new materials, designs and manufacturing technologies of individual elements and lamps in whole [1,2]. As for the grids, it is worldwide accepted the only right direction -use of a wide range of coatings that meet the following requirements: high value of the emissivity, getter properties, low vapor pressure at operating temperature, ability to form stable solid solutions with condensable products of the thermionic cathode evaporation and a high work function to impart the surface of the electrodes with anti-emission properties [4].…”

Impedance matching network systems using stub-lines of 20 kW CW RF amplifier for SKKUCY-9 compact cyclotron

“…It makes RF power signal stably [5]. In addition, it has an advantage due to the endurance breakdown of the reflected power generated by the impedance mismatch [6]. The 3CW20000A7 is operated in the B-class grounded grid.…”

Operation Experience of Tetrode Vacuum Tubes in J-PARC Ring RF System

“…One of them caused an abnormal increase of filament current in a day, and the other caused a remarkable reduction of cathode current. The lifetime of the tube strongly depends on electron emission life from the filament [5,6]. A thoriated tungsten filament is employed in TH589, where the thorium helps to reduce a working function of the electron emissions on the tungsten surface.…”